ARC Welding Aluminum

[Simon Strauss]

Let me start this out by saying that i have never used an arc welder before nor do i have any idea how one works at the moment(i plan on looking it up after i post this).

That being said today as we were cleaning out our shop and going through all the stuff that maintenance had put there over the summer we found an arc welder that they said we could have. Now the question is do we have any use for it, the mentor who is going to teach me how to use it has never tried arc welding on aluminum and I'm wondering if it would work. Do any of you have experience in this and is there any sort of technique i should use?

Thanks, Simon

[KenWittlief]

Straight arc welding, with a stick welder, Im pretty sure the answer is no. You can weld steel with it, you can even braze with it

but when you get aluminum hot enough to melt it combines with the oxygen in the air and turns to a white powder / dust.

Aluminum is normally welded with a MIG welder using an inhert gas. This is a type of arc welder that feeds wire from the center of a handle. It is also connected to a cylinder of argon or carbon dioxide. As you weld the gas flows out over the weld in progress, keeping it in an envelope of the inhert gas. Since no oxygen is present, the alum does not oxidize into dust.

Its also great for welding steel and stainless steel, because you do not need flux wire or flux core welding sticks (which cover the weld with a crusty ceramic like covering to keep it from oxidizing while it cools)

someone correct me if Im wrong on this - technology keeps changing so fast - but Im pretty sure you need a gas envelope MIG wire welder to weld aluminum

But even if it is a plain old stick arc welder, Im sure you will find many uses for it for your team. If steel is too heavy for most of your robot components and chassis, you could still use it for making a robot cart, special tools, or small metal parts on the robot.

[Gabe]

Yes you can, but I have never heard of it being recommended. Aluminum arc welding rods can be bought, but are only meant for a welder that has a direct current output or has direct current capability. It is easy to know if your welder is the right one because it will be labeled so. As for buying rods, you can buy them from welding supply stores, but the easiest is to buy it from McMaster-Carr. Their website is here: http://www.mcmaster.com/
Search their site looking for arc welding electrodes. The specific electrode you are looking for is specialty electrode E4043. The E means it is a electrode and the 4043 is the number for that specific aluminum alloy. It will be $15 for a half pound of welding rods, and there are 35 to 50 rods per pound.

However, I must add that since you have never used an arc welder before, learning to weld using aluminum rods might end up being very discouraging. Practice with steel first and steel welding rods to get the feel of it, then try aluminum. And always, tell us how it goes!

[KenWittlief]

ok, Gabe is right. You can buy alum rods for a stick welder

but.... like he said, they seem to be used only when you have no other choice.

I googled this website up, they seem to know what the deal is:

http://www.weldingweb.com/showthread.php?t=2641

[sanddrag]

Originally Posted by KenWittlief

Aluminum is normally welded with a MIG welder using an inhert gas. This is a type of arc welder that feeds wire from the center of a handle. It is also connected to a cylinder of argon or carbon dioxide. As you weld the gas flows out over the weld in progress, keeping it in an envelope of the inhert gas. Since no oxygen is present, the alum does not oxidize into dust.

I believe the preferred method of welding aluminum is with a TIG welder, unless it is a high volume production shop or really long beads. The problem with MIG welding aluminum is feeding the wire. It is very soft and tends to bunch up. If you keep the gun hose totally straight, it may work. When MIG welding aluminum, a spoolgun is the weapon of choice. This puts the wire right on the gun so it has a very short distance to feed. Unfortunately spoolguns are usually many hundreds of dollars.

Aluminum is usually welded with 100% Argon shielding gas.

The nice thing about stick welders is that you get the most power for your dollar, and you don't need to worry about wire speed and shielding gas and that sort of thing. You will have to chip off slag though. It is possible to make some really nice welds using a stick welder, but it takes practice. Vertical and overhead welding is definitely much easier with a MIG.

For stick (arc) welding aluminum, I know they make the rods, but I haven't heard any stories from anyone who's used them. If you try it out, be sure to let us know!

[woodman]

Tig is best choice-has the best penetration. Mig will work great. We used migs on production line with no problem welding aluminum doors for RV's. Migs have less penetration than tig. Arc can be done, but its tricky. Welded up some guards for some saws without much trouble. I have had better luck welding heavy wall aluminum tube with aluminum stick. Those guards were .125 sheet, and used 5/32 rod and it worked OK. I work in the maintenance field and do some welding almost every day. In my job I have used all 3 methods of welding aluminum. If you can, tig it.
Dennis

[sanddrag]

Originally Posted by woodman

Mig will work great. We used migs on production line with no problem welding aluminum doors for RV's.

Were you using a spool gun? If not, did you make any changes to allow you to feed the aluminum wire?

[woodman]

We used a couple of spool guns in the main weld shop. In the door assembly area we had 4 welders that was "right out of the box". All standard equipment. One of these welders we would change over when needed (aluminum-mild steel) by changing wire and gas. We used same guns and whips.

Originally Posted by sanddrag

Were you using a spool gun? If not, did you make any changes to allow you to feed the aluminum wire?

[eugenebrooks]

I mentor the weiding on Team 1280's robot and do the welding myself when a gifted student is not available to do it under my supervision. When it comes to the typical thickness of aluminum used on a FIRST robot, TIG with a suitably high current is the best choice. A 175 amp welder is marginal for some configurations of 1/8 aluminum and is pretty useless on 1/4 inch thick aluminum. This should give you an idea of what your welder is capable of if you know its current rating. MIG would be a second choice, but there are significant wire feeding issues for aluminum welding with MIG, so a setup specifically for aluminum is best.

I have tried using the specialty arc welding rods for aluminum in the distant past and the results were so poor that I would not try them again. Your arc welder is best confined to mild or carbon steel, and there wlll be times that you need to weld a steel part so it is a good capabilty to have.

[Peter Matteson]

Just some added info. TIG (Tungsten Inert Gas for those that don't know the accronym) allows the welder to better control the heat input with the torch so that they can better control the heat affected zone and minimize warping the metal.

Also I wouldn't suggest MIG (moving inert gas) welding a long seam straight through as the distortion will significant. It would be better to use a back-stich technique to minimize the thermal effects.

[KenWittlief]

Originally Posted by Simon Strauss

...the mentor who is going to teach me how to use it ...

If you have the opportunity to learn to weld, even if its only practice on scrap metal, definately take advantage of it.

Welding is something that every person with a creative or mechancial aptitude should learn.

[Dick Linn]

Do learn to weld. If it's an ac/dc box, you can stick weld aluminum using DC, but it takes a lot of practice from what I read. You can also convert it to a TIG unit, though you'd need to add a high frequency box to do AC. Search around on http://www.hobartwelders.com/mboard/ There are some expert professional welders that frequent that site.

[eshteyn]

If your are careful enough you can weld aluminum with an arc welder. I have tried with a TIG, MIG, and even a Stick welder. The only thing you really have to watch out for and always remember to check is the guidelines on the welder for your material and thickness of material. My recommendation would be using a MIG welder because its it easier. If the only thing you have is a TIG welder then practice on some spare material and make sure you have your feed speed right for the material and amperage your using. I like to feed the aluminum welding stick in a way to create a ball pattern one on top of the other, this makes for a good complete weld and it also looks very nice.